Flutter Firestore Query Nested Subcollections

问题

I am trying to query subcollection in Firebase, but I always get an empty list...

This is my query:

Firestore.instance.collection('messages').where('idFrom', isEqualTo: userID).snapshots();

I know that I have subcollection with another subcollection here..

/messages/RWzG98s92mVTZniofez6YoYsNhA3-tT2Q16n1FMZoTNZQOejtWuJdCmD2/RWzG98s92mVTZniofez6YoYsNhA3-tT2Q16n1FMZoTNZQOejtWuJdCmD2/1579394957103

And my question is how to query these types of models?

回答1:

Since Firstore queries are always shallow, you have to build the path to the subcollection to query.

Firestore.instance
    .collection('messages')
    .document(...)   // ID of the nested document
    .collection(...).  // ID of the nested subcollection
    .where('idFrom', isEqualTo: userID);

There is no way to avoid giving those nested IDs. If you can't identify the full path of the subcollection to query, you won't be able to access its documents.

来源：https://stackoverflow.com/questions/59811699/flutter-firestore-query-nested-subcollections